Numb (U2 Song) - Recording and Production

Recording and Production

"Numb" originated as a discarded song from the Achtung Baby sessions called "Down All the Days" (later released in the premium editions of Achtung Baby's 20th anniversary reissue) that was recorded with producer Daniel Lanois at Berlin's Hansa Studios. The band was not fond of the track—Zooropa co-producer Flood, who was engineer for the Achtung Baby sessions, said it was "quite a ballady song and in the end it was decided that it didn't fit" on that record. Guitarist The Edge said, "It almost worked," calling it a "quite unhinged electronic backing track with a very traditional melody and lyrics" sung by lead vocalist Bono.

During the Zooropa sessions of February–May 1993, U2 revisited the song. At Windmill Lane Studios, producer Brian Eno began working with a stereo submix of the Berlin version, containing guitar, bass, bass pedals and drums, that Flood had created. Eno added about six or seven tracks of keyboards to the submix, mostly samples and strings from a Yamaha DX7 synthesiser. Some of the samples included Arabic voices and congas. According to Flood, "The idea of his overdubs was to make up music out of non-musical noises, like loops of pieces of dialogue and video samples." The Edge called Eno's additions "fantastic".

The song's biggest contribution came while the band were organizing the final running order for Zooropa. The Edge spent several hours in another studio with the mix demoing ideas, eventually adding vocals in a monotone, almost rapped delivery. He said that writing the lyrics "came very quickly", and that he wrote so many lyrics that two verses had to be cut from the song. His vocals were recorded at Westland Studios in Dublin, where the band spent one day for the album sessions. Flood subtly added gating to his voice "to turn the level down when he wasn't singing." The addition of The Edge's vocals, for the most part, completed "Numb".

Bono and drummer Larry Mullen Jr. provided backing vocals. Flood treated Bono's vocals with heavy reverb to compliment his "falsetto soul voice", while Mullen provided two tracks of backing vocals, one with a falsetto and one with his natural singing voice. After the vocals were overdubbed, Flood and The Edge mixed the track at Westland Studios. The Edge described it as "a few hours' work and a lot of editing", but said the mixing was "the easiest thing in the world" Flood concurred, calling the mixing "very straightforward". A sample of a Walkman cassette player rewinding was accidentally recorded onto the audio tapes, but the group liked the sound and looped it throughout the song. The final mix comprised about 15 or 16 audio tracks.